In　this　paper,　the　cooperative　semi-global　robust　output　regulation　problem　for　the　nonlinear　lower　triangular　uncertain　multi-agent　systems　with　nonidentical　relative　degrees　is　studied.　We　first　introduce　a　type　of　distributed　internal　model　to　convert　the　cooperative　semi-global　robust　output　regulation　problem　into　the　cooperative　semi-global　robust　stabilization　problem　of　its　associated　augmented　system.　We　then　solve　this　stabilization　problem　by　developing　the　block　semi-global　backstepping　control　technique　under　some　standard　assumptions.　©　2015　IEEE.